First time I got 4670, Catalyst was only option and it hanged the system when I switched from Xorg to TTY1.
Next, in a year when I got 4770, I had ~5 fps with open driver in OpenArena, but 2D was usable! I did not install catalyst here even once.
The time when I sold the card, it had already 30fps in openarena, that was 2011.
Now open driver achives ~100fps with this card and runs ~70% of catalyst. It is very very stable driver, with less bugs than nvidia closed source.
By the way, I used nouveau on 260GTX and its running fine. The problem is, closed driver is too very polished. Maybe I need to retest it before it gets sold. I am selling it now.
I would donate it instead, but its running ok already and there are virtually no differences between G200a/b and G92.
When I get my Vishera system, I will donate 50€ - the price of 260GTX, to Marek, sooner if he improves something for 5xxx-6xxx GPU.
As a rule of the thumb, you should donate 20% of card cost to opensource team for *the* driver.
So you are fine sitting on nvidia with closed source driver, well, ok, enjoy sitting there. I had already one old machine with 6100 nvidia IGP, that didn't work with ANY closed source driver, but nouveau works like a miracle there!
When you get this experience, you will change your stance.
Why do you think overclocking was disabled on closed source driver by nvidia on fermi+ ?
Precisely to make nouveau driver perform like crap due to low GPU clocks. So that you stay with closed source driver.